acanthosis nigricans

Acanthosis nigricans is a skin condition involving a characteristic velvety thickening of the skin, most often and most visibly on the nape of the neck. It is seen most frequently in obese children, and is associated with insulin resistance (high insulin levels caused by chronically increased blood sugar levels) and is a marker for the so-called metabolic syndrome.

The affected skin becomes darkened, with velvet-feeling raised plaques of skin at the nape of the neck, and less often in the underarm area, the skin in the skin crease under the breasts, in the groin and inner thighs, and around the anus and genitals.

The condition is most often associated with obesity, but occurs in many other conditions as well. However, it is thought that high insulin levels associated with these other conditions produce the characteristic skin findings. There is a rare familial form of the condition as well.

Acanthosis nigricans is difficult to treat dermatologically. Addressing the underlying problems of obesity is probably most important.

Pseudoacanthosis nigricans is the term used for acanthosis nigricans found in obese but otherwise normal children.